Certain classes of electronic equipment have an expandable feature which in turn necessitates the use of additional connectors for bringing in signals and additional power. These needs can be filled in a variety of ways, one of which is to build the basic system with all of the possible connectors that can be used fitted onto the system at the time of manufacture. The cost associated with doing this, aside from the efficiencies, make this a highly undersirable option. It is more desirable to have a system wherein the customer can add connectors of the particular type and quantity desired at any time and or rearrange the connectors without the need of special tools and fabrication techniques.
An additional problem arises when the back panel of the electronic equipment has to remain electrically secure from radio frequency emissions, that is, the back panel has to be a shield with no openings through which radio frequency emissions can pass. Furthermore, there is the problem that is associated with grounding in that it is advantageous from an electrical point of view to have the connector and its housing grounded to the potential of the back panel.
A patent of interest for showing the mounting of electrical connectors to panels is represented by U.S. Pat. No. 2,538,489, entitled "Instrument Panel for Accommodating Changeable Arrays of Instruments", by S. A. Walton. The instrument panel disclosed in such patent consists of a metallic frame having parallel rails spaced apart so as to accept electrical components that may be mounted between the rails at desired positions, with each component having a mounting element which assures the positioning of the component between the rails even though there is a difference in size between the electrical components. A mask made of a non-trasparent material, such as plastic, has openings cut therethrough to correspond to the positioning and outline of the electrical components on the panel so as to hide the supporting elements and thereby make a more visually pleasing appearance.
Another patent of interest is U.S. Pat. No. 3,289,043 entitled "Selectable Plug-In Assembly", by E. J. Nielsen. The assembly of this patent is comprised of a plurality of terminal blocks which are each connected to an associated electronic circuit such that a customer may assemble the components and the terminal blocks in a useful configuration and, through push pin connectors insertable into receptacles located in the terminal blocks, cause specific interconnections amongst the electronic components. With the desired interconnections in place, the assembly may be encapsulated to provide a structure which is economical and relatively easy to assemble and manufacture.
Another patent of interest is U.S. Pat. No. 4,131,330, entitled "Mounting Device for Electrical Connectors", by L. J. Stupay. In such patent a mounting device is disclosed for supporting electrical connectors, of an elongated configuration, of a first type, in one portion of the mounting panel and for supporting electrical connectors of a second type in another portion of the panel. Protective wiring covers are provided for shielding the wiring from abrasion and contact with other adjacent members.
A further patent of interest is U.S. Pat. No. 4,353,614, entitled "Unitary Molded Plastic Connector Plug Support Member", by J. O. Etchison, Jr. et al. The invention disclosed in the patent is a molded plastic back plane which has a number of defined elongated openings for receiving like shaped electrical connectors. A feature of the invention is the ability to mount the connectors onto the back plane and have the connectors partially wired at a location differing from where the bay (cabinet9 frames are assembled. The units can then be shipped to a central location where the partially wired back plane can be assembled in the bay fram and the wiring completed.
The aforementioned patents set forth, as an underlying tone, the desirability of flexibility when it comes to wiring and inserting connectors onto back planes of electronic hardware. The inventors of the present invention have directed their efforts towards a versatile system permitting virtually unlimited expansion and combinations by a customer without the need for specialized assembly equipment.